Which statement is an examples of a beneficial mutation?

A person has a mutation that causes him to be unable to fully digest lactose.
A fawn in the forest has a mutation they causes it to be more resistant to pesticides.
A mosquito had a mutation that causes it to be more resistant to pesticides.
A person has a mutation that causes her earlobes to be attached to her head.

A fawn in the forest has a mutation that causes it to be more resistant to pesticides is an example of a beneficial mutation.